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391145ba2a
BPF kfuncs are meant to be called from BPF programs. Accordingly, most
kfuncs are not called from anywhere in the kernel, which the
-Wmissing-prototypes warning is unhappy about. We've peppered
__diag_ignore_all("-Wmissing-prototypes", ... everywhere kfuncs are
defined in the codebase to suppress this warning.
This patch adds two macros meant to bound one or many kfunc definitions.
All existing kfunc definitions which use these __diag calls to suppress
-Wmissing-prototypes are migrated to use the newly-introduced macros.
A new __diag_ignore_all - for "-Wmissing-declarations" - is added to the
__bpf_kfunc_start_defs macro based on feedback from Andrii on an earlier
version of this patch [0] and another recent mailing list thread [1].
In the future we might need to ignore different warnings or do other
kfunc-specific things. This change will make it easier to make such
modifications for all kfunc defs.
[0]: https://lore.kernel.org/bpf/CAEf4BzaE5dRWtK6RPLnjTW-MW9sx9K3Fn6uwqCTChK2Dcb1Xig@mail.gmail.com/
[1]: https://lore.kernel.org/bpf/ZT+2qCc%2FaXep0%2FLf@krava/
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20231031215625.2343848-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
118 lines
3 KiB
C
118 lines
3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Unstable Fou Helpers for TC-BPF hook
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*
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* These are called from SCHED_CLS BPF programs. Note that it is
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* allowed to break compatibility for these functions since the interface they
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* are exposed through to BPF programs is explicitly unstable.
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*/
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#include <linux/bpf.h>
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#include <linux/btf_ids.h>
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#include <net/dst_metadata.h>
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#include <net/fou.h>
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struct bpf_fou_encap {
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__be16 sport;
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__be16 dport;
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};
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enum bpf_fou_encap_type {
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FOU_BPF_ENCAP_FOU,
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FOU_BPF_ENCAP_GUE,
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};
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__bpf_kfunc_start_defs();
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/* bpf_skb_set_fou_encap - Set FOU encap parameters
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*
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* This function allows for using GUE or FOU encapsulation together with an
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* ipip device in collect-metadata mode.
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*
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* It is meant to be used in BPF tc-hooks and after a call to the
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* bpf_skb_set_tunnel_key helper, responsible for setting IP addresses.
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*
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* Parameters:
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* @skb_ctx Pointer to ctx (__sk_buff) in TC program. Cannot be NULL
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* @encap Pointer to a `struct bpf_fou_encap` storing UDP src and
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* dst ports. If sport is set to 0 the kernel will auto-assign a
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* port. This is similar to using `encap-sport auto`.
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* Cannot be NULL
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* @type Encapsulation type for the packet. Their definitions are
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* specified in `enum bpf_fou_encap_type`
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*/
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__bpf_kfunc int bpf_skb_set_fou_encap(struct __sk_buff *skb_ctx,
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struct bpf_fou_encap *encap, int type)
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{
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struct sk_buff *skb = (struct sk_buff *)skb_ctx;
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struct ip_tunnel_info *info = skb_tunnel_info(skb);
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if (unlikely(!encap))
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return -EINVAL;
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if (unlikely(!info || !(info->mode & IP_TUNNEL_INFO_TX)))
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return -EINVAL;
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switch (type) {
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case FOU_BPF_ENCAP_FOU:
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info->encap.type = TUNNEL_ENCAP_FOU;
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break;
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case FOU_BPF_ENCAP_GUE:
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info->encap.type = TUNNEL_ENCAP_GUE;
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break;
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default:
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info->encap.type = TUNNEL_ENCAP_NONE;
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}
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if (info->key.tun_flags & TUNNEL_CSUM)
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info->encap.flags |= TUNNEL_ENCAP_FLAG_CSUM;
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info->encap.sport = encap->sport;
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info->encap.dport = encap->dport;
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return 0;
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}
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/* bpf_skb_get_fou_encap - Get FOU encap parameters
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*
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* This function allows for reading encap metadata from a packet received
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* on an ipip device in collect-metadata mode.
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*
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* Parameters:
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* @skb_ctx Pointer to ctx (__sk_buff) in TC program. Cannot be NULL
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* @encap Pointer to a struct bpf_fou_encap storing UDP source and
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* destination port. Cannot be NULL
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*/
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__bpf_kfunc int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx,
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struct bpf_fou_encap *encap)
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{
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struct sk_buff *skb = (struct sk_buff *)skb_ctx;
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struct ip_tunnel_info *info = skb_tunnel_info(skb);
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if (unlikely(!info))
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return -EINVAL;
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encap->sport = info->encap.sport;
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encap->dport = info->encap.dport;
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return 0;
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}
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__bpf_kfunc_end_defs();
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BTF_SET8_START(fou_kfunc_set)
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BTF_ID_FLAGS(func, bpf_skb_set_fou_encap)
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BTF_ID_FLAGS(func, bpf_skb_get_fou_encap)
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BTF_SET8_END(fou_kfunc_set)
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static const struct btf_kfunc_id_set fou_bpf_kfunc_set = {
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.owner = THIS_MODULE,
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.set = &fou_kfunc_set,
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};
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int register_fou_bpf(void)
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{
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return register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS,
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&fou_bpf_kfunc_set);
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}
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